单项选择题
A.3~5s B.5~10s C.10~15s D.25~35s
A.线路瞬间故障 B.线路永久故障 C.值班员合闸断路器,线路有故障,引起断路器跳闸
A.≥10MΩ B.≥20MΩ C.≥30MΩ D.≥50MΩ